1. Field of the Invention
The present invention relates to formation of nanowires, and more particularly, to a method and apparatus capable of synthesizing high-density wires in the inner pores and on surfaces of a variety of porous materials.
2. Description of Related Art
Recently, many studies are being performed on the synthesis of one-dimensional nano-structures. Among the nano-structures, nanowires exhibit new optical, electrical and mechanical properties compared to existing bulk-size materials. Therefore, active studies on nano technology are being carried out in many countries.
Nanowires are attracting strong interest, since they have unique optical and electrical characteristics compared to physical properties of bulk materials. Since silica nanowires emit strong blue light, it is possible to develop a nanoscale optical device using this property. In addition, when silica nanowires are used for a waveguide that is a transmission line for a high-frequency bandwidth, the loss ratio is low and the use of high power is possible. In addition, application of silica nanowires to a scanning near-field optical microscope (SNOM) that requires a tip of a microscopic hole can lead to high definition by overcoming the limited diffraction of quantum.
In order for such materials to be applied, the properties of nanowires, or a nano-material having a one-dimensional structure, must be precisely controlled in optical and electrical methods, and a variety of studies on the method of synthesizing nanowires are being carried out.
According to a related-art method of synthesizing silica nanowires, SiH4 is used as a source gas. However, the high price of the SiH4 gas is burdensome due to a shortage since this gas is used as an essential raw material in the photovoltaic industry and for the fabrication of semiconductor wafers. In addition, the SiH4 gas is harmful, which leads to the problem in that a separate safety device must be added for the supply of the SiH4 gas. Due to these problems, the need for a material that can be a substitute for SiH4 is increasing.
Another related-art method of fabricating silica nanowires involves loading silicon powder into a chamber and evaporating the silicon powder through heat. In this case, however, the process must involve raising the temperature until the silicon powder has evaporated, and concentric evaporation is not realized at a specific point in time. Therefore, it is difficult to control the process. In addition, this method uses catalyst in most cases, and the catalyst can be contained in silica nanowires as impurities. This also requires an additional process of removing the catalyst, which is problematic.
In addition, porous ceramic filters or the like are used for filtering exhaust gas from vehicles. These filters include nanowires, such as whiskers, grown inside the pores. In addition, when nanowires are formed inside the pores of porous structural materials, the effect of increased strength can also be obtained.
A related-art method of growing such wires includes placing a porous substrate inside a reaction chamber and blowing a source gas into the reaction chamber, thereby growing wires on the porous substrate under specific conditions (e.g. refer to Korean Patent No. 10-753114). However, process conditions where wires are actually grown are complicated. When such conditions are not satisfied, wires are grown into the shape of a pressed film when observed with a microscope and fail to obtain expected advantages, which is problematic. In addition, there is another limitation in which the structural shape of wires grown on the surface of the substrate or the surface of the pores is not controlled.
The information disclosed in the Background of the Invention section is provided only for better understanding of the background of the invention, and should not be taken as an acknowledgment or any form of suggestion that this information forms a prior art that would already be known to a person skilled in the art